Sunflower Insect Pest Management - USDA ARS...Future for Sunflower IPM . Compared to most row crops...
Transcript of Sunflower Insect Pest Management - USDA ARS...Future for Sunflower IPM . Compared to most row crops...
Sunflower Insect Pest Management
Larry Charlet USDA, ARS Northern Crop Science Lab
Fargo, North Dakota
Outline of Presentation
Sunflower history & characteristics Pest complex & damage Insect pest management strategies Future for Sunflower IPM
Origin of Sunflower
Native to North America 51 species in genus Helianthus Food source for Native Americans & domesticated in central US before 3000 BC Introduced to Spain in early 1500s Spread across Europe & adopted as crop in Russia in early 1800s Reintroduced into US in 1880s Sunflower production developed in Canada in 1950s & US in 1970s
Possible Reasons for Insect Problems in Sunflower
Sunflower native to North America Pests specific to sunflower Change in plant architecture Monocultures Breeding for vigor, yield, uniformity
oil content, etc. Ineffective natural enemies
Native & Cultivated Sunflower
Plant architecture Multiple vs. single head Branched vs. single stem Small vs. large seeds
Growth phenology Variable vs. discrete emergence Extended vs. short flowering period
Plant community Mixed vs. monoculture Small patches vs. large acreages Low vs. high density
Insects attacking the sunflower head & seeds
Sunflower moth Lygus bug
Banded sunflower moth
Red sunflower seed weevil
Sunflower midge
Insects attacking the sunflower leaves & stem
Sunflower beetle Sunflower stem weevil
Palestiped flea beetle
Sunflower stem girdler or long-horned beetle
Seedlings & roots attacked: wireworms, cutworms
Sunflower beetle Red sunflower seed weevil Sunflower midge Banded sunflower moth Lygus bug Palestriped flea beetle
Sunflower moth Sunflower stem weevil Sunflower long-horned beetle
Distribution of Sunflower Insect Pests
Sunflower Beetle
egg
larvae
adult
Adults feed on leaf margins during the day & larvae over leaf surface at night
Overwinter as adults in soil
Eggs laid on stem or underside of leaves
Stem Weevil Biology
Overwintering chambers
weakens the structure of the stalk which can result in lodging
deposited around cotyledon or lower stem
feed & develop in sunflower stem
Adult Eggs
Larvae
Lodging prior to harvest caused by larval overwintering chambers (20-30 per stalk), stalk characteristics, & weather
Sunflower Stem Weevil Damage
Lodged fields in North Dakota
X-section with larvae
Split stalk with larvae
1/8-inch long
Palestriped Flea Beetle
Adult Feeding damage on seedling sunflower
Sunflower Long-horned Beetle
Lodged field in Texas 1980s
Stalk broken at soil level
Adult
Larvae
adult
nymph
Lygus Plant Bugs Adults
Small, cryptically colored insects Distinctive yellow triangle or “V” Pale green to reddish-brown
Immatures (nymphs) Look like aphids
Brown spot on confection kernels
Red Sunflower Seed Weevil
adult
larva
Females require pollen to mature eggs Oviposit during flowering Heads with 50% flowering preferred Eggs laid inside seed Larvae in outer seed rows Kernel 1/3 consumed
Drop into soil to overwinter
Exit holes
Banded Sunflower Moth
larva
Adult
Damaged seeds
Exit holes
Sunflower Moth
Adults attracted to blooming heads Eggs deposited on heads & hatch
in 4-5 days Larvae feed on pollen, disk flowers,
& mature seeds Mature larvae move to soil
& spin cocoons to overwinter
Overwinter in Texas adults migrate to central & northern Plains on southerly winds
Webbing & frass may occur in areas on head & Rhizopus head rot is often associated with infestations
Adult Larvae
Infested bud
Adults
Sunflower Midge
Eggs
Larvae
Heavily damaged heads: gnarled & cupped with few seeds produced
Necrotic tissue under bracts caused by larval feeding; loss of ray flowers
Cutworms
Early season pest on seedlings Localized, erratic infestations
Red-backed cutworm June
Dingy cutworm May
Wireworms Early season pest on
seedlings Localized infestations Concern – increasing
populations due to more no-till acreage, land coming out of CRP
Sunflower Insect Management
Identification of pest Knowledge of pest biology Economic/treatment thresholds Field monitoring/sampling Management tactics include: Plant resistance Cultural control Biological control Chemical control
Chemical Control
Has long been primary tactic for managing pests Effective, but expensive & has nontarget impacts:
resistance, secondary pests, pest resurgence, destruction of pollinators & natural enemies, environmental contamination
Destruction of pollinators can reduce fertilization & thus lower yield > pest infestation alone Pesticides should be used in combination with other
tactics & only when pests exceed thresholds Because of ease of use & ability to quickly destroy
pests continues to be primary management focus for producers
Uses plant’s own defense (antibiosis, antixenosis, tolerance)
Developed through plant screening & breeding Cost effective & environmentally safe Usually compatible with other approaches
(evaluate for impact on natural enemies)
Plant Resistance
Challenges Evaluating Sunflower for Insect Resistance
Variable insect population pressure Year to year densities often unpredictable Coordination of insect presence/attack & plant
phenology Environmental & biotic limitations Drought or excessive moisture & wind Birds Plant disease
Labor (time & costs) in determination of insect damage Post-harvest evaluation
Cultural Control
Include: planting date, tillage, trap crops, rotation, crop spacing/population, intercropping, sanitation Advantage of no additional equipment, usually no side-effects, simple, inexpensive Need advance planning, control not complete, detailed knowledge of pest required
Biological Control
Importation & establishment of exotic species Augmentation Conservation – manipulate
environment to reduce nontarget effects from pesticides & other adverse factors Predators, parasitoids & pathogens Study natural enemies & how
to protect & utilize them in managing pests
Biological Control of Sunflower Insect Pests
Many natural enemies have made the transition along with their hosts from native to cultivated sunflower Many potential pests held in check by beneficials Natural enemies known for major pest species predators & parasitoids have been studied little known about pathogens
Research has revealed regional differences in parasitoid species richness Studies also show some parasitoids attacking pest species in native sunflowers not present in agroecosystem
Sunflower Insect Natural Enemies
Sunflower beetle predators
Banded sunflower moth parasitoid
Sunflower stem weevil parasitoid Red sunflower
seed weevil parasitoid
Current IPM Practices for Sunflower Insect Pests
Knowledge of pest biology & damage Economic thresholds developed for all except – sunflower midge Scouting methods have been developed, but are inadequate for some species & need to be refined Management strategies: Chemical control most frequently used
Pyrethroids Cultural control
Planting date effective for: banded sunflower moth, sunflower stem weevil, sunflower
moth, sunflower beetle & red sunflower seed weevil
Future for Sunflower IPM
Compared to most row crops sunflower is relatively new Research dates only to late 1960s (Texas & North
Dakota) Potential sources of germplasm for resistance: 51 native species of sunflower USDA Plant Introduction Station
1600+ cultivated accessions 2000+ wild accessions
Improve biological control through conservation, augmentation, or search for new beneficials Refine EIL, sampling, cultural control strategies (trap cropping), reduce pesticide use, & integrate methods to lower production costs